Happily, however, one of his complaints is not waffly and opinion based - it's demonstrably wrong. And it's this one...
He attacks claims that modernisation brings with it a slow sapping of religion. Now, you may think that's a slam dunk, but unfortunately Prof Gray is not up to speed with the facts. Here's what he says (my emphasis):
The positivists believed that with the development of transport and communication - in their day, canals and the telegraph - irrational thinking would wither way, along with the religions of the past. Despite the history of the past century, Dennett believes much the same. In an interview that appears on the website of the Edge Foundation (edge.org) under the title "The Evaporation of the Powerful Mystique of Religion", he predicts that "in about 25 years almost all religions will have evolved into very different phenomena, so much so that in most quarters religion will no longer command the awe that it does today". He is confident that this will come about, he tells us, mainly because of "the worldwide spread of information technology (not just the internet, but cell phones and portable radios and television)". The philosopher has evidently not reflected on the ubiquity of mobile phones among the Taliban, or the emergence of a virtual al-Qaida on the web.
Now, I don't know the statistics of mobile phone use among the taliban (and neither does Gray), but I do have data on the number of telephone lines and mobile phones per capita in a variety of countries around the world (including Afghanistan). You can download them youself from the US Government Census). And there are also national-level data on a number of religious variables, such as the number of people who pray (a better indicator of belief than just asking people if they believe). These can be obtained from the World Values Survey and the International Social Survey.
Put these data together, and you get the graph shown. A clear and strong link: as the number of phones goes up, the number of people who pray goes down. Now, there are a number of possible reasons for this link. It's likely a mostly indirect effect - the richer a nation is, the more phones. So there may be an effect of wealth (although the correlation with phone lines is actually stronger than the correlation with per capita GDP). The number of phone lines is also correlated with other factors, such as education and literacy.
But, crucially, these are all indicators of modernisation themselves. So, Prof Gray, you are wrong on this count. Modernisation is sapping away at religion, and it will continue to do so.